Doherty also shared a photo of herself getting injections. "The many faces of cancer. Chemo Day. What we call the Red Devil being injected into me via the port that's in my chest," she captioned the image. "Dawn is my nurse who takes excellent care of me August 10, 2016 #cancersucks #fightlikeagirl"

Earlier this summer, the 45-year-old actress revealed in an exclusive interview with ET that her cancer had spread. "From one of my surgeries, we discovered that some of the cancer cells might have actually gone out of the lymph nodes," Doherty explained. "So for that reason, we are doing chemo, and then after chemo, I'll do radiation."

"The unknown is always the scariest part," Doherty added. "Is the chemo going to work? Is the radiation going to work? You know, am I going to have to go through this again, or am I going to get secondary cancer? Everything else is manageable. Pain is manageable, you know living without a breast is manageable, it's the worry of your future and how your future is going to affect the people that you love."

Last week, ET obtained documents confirming that Doherty had settled a legal battle with her former management firm. Doherty sued Tanner Mainstain, claiming Mainstain allowed her insurance coverage to lapse, which she says kept her from a regular checkup, thus causing her cancer to go undiagnosed. The actress landed a settlement in the $15 million suit, but the amount is undisclosed.